In a manufacturing process of a substrate such as a semiconductor wafer, a polishing step of polishing a film of a metal or the like formed on the substrate is included, and after the polishing step, washing for removing fine particles as polishing chips is performed. For example, in a damascene wiring forming step of forming a wiring by embedding a wiring groove formed inside an insulating film of the substrate surface with metal, excess metal of the substrate surface is polished and removed by chemical mechanical polishing (CMP) after forming the damascene wiring. Since particles (defect), such as residues of the slurry (slurry residues) or metal polishing chips used in the CMP, are present on the substrate surface after the CMP, it is necessary to remove these by washing.
When the residues remain on the substrate surface due to the insufficient washing of the substrate surface, there is a problem in terms of reliability, such as an occurrence of leakage from the remaining portion of the residues on the substrate surface, or the cause of adhesion failure. Therefore, it is necessary to wash the substrate surface, from which a metal film, a barrier film, an insulating film or the like is exposed, with high washing degree. In recent years, with the miniaturization of semiconductor devices, the diameter of particles to be removed has decreased, and the request for washing has also become strict.
As a washing method after the polishing in the CMP device, washing using a roll washing member, washing using a pencil washing member, washing using a two-fluid nozzle and the like have been known. In these types of washing, the substrate is rotated about its central axis, and a chemical liquid and a rinse liquid (hereinafter, the chemical liquid and the rinse liquid are collectively referred to as a “washing liquid”) are supplied to the surface (upper surface) of the substrate. Moreover, in these types of washing, after the washing (chemical liquid washing) is performed by the action of the roll washing member, the pencil washing member and the two-fluid nozzle, at least the rinse liquid is supplied as a washing liquid, and the washing (rinsing washing) performed without the action of the roll washing member, the pencil washing member and the two-fluid nozzle is performed.
As the methods of supplying the washing liquid onto the surface of the substrate, a method of discharging a washing liquid from a single tube nozzle to land on the substrate surface, a method of spraying the atomized washing liquid from the spray nozzle to land on the substrate surface, a method of discharging the washing liquid from a porous tube nozzle (bar nozzle) to land on the substrate surface and the like are known. The washing liquid supplied to the surface of the substrate receives the centrifugal force due to rotation of the substrate to flow toward the outer circumference of the substrate. In addition, the flow of the washing liquid after landing on the substrate is affected not only by the centrifugal force, but by the inertia of the flow when there is a flow in the washing liquid in a direction parallel to the surface of the substrate prior to landing on the surface of the substrate, and when the surface of the substrate is inclined, the flow of the washing liquid is affected by gravity, and a contact angle between the washing liquid and the surface of the substrate also becomes a factor that determines the flow of the washing liquid.
Regardless of the chemical liquid washing or the rinsing washing, when there is a location at which the flow of washing liquid is small or a location at which the washing liquid stagnates in a part of the substrate, particles, such as slurry residues and metal polishing chips, still remain in the portion, and the washing becomes not sufficient. Thus, it is desirable that the washing liquid uniformly flow over the entire radius of the substrate.
With the miniaturization of the recent semiconductor devices, there have been increasing demands for the washing degree of the washing device. However, in the conventional washing device, the removal of the fine particles (for example, particles of 65 nm or less) is very difficult. In particular, when the diameter of the substrate becomes 450 mm in the future from 300 mm which is currently the mainstream, such insufficient washing becomes remarkable in a part of the substrate.
The problem of having difficulty in removing the fine particles will be described by way of an example of the case where the horizontal flat substrate is rotated to perform the rinsing washing of the substrate surface. In the rinsing washing which removes the residual particles and the residual chemical liquid, when landing the rinse liquid discharged from the single tube nozzle to the vicinity of the center of the substrate by adopting a method of discharging the rinse liquid from the single tube nozzle to land on the substrate surface, although relatively high washing degree can be obtained in the vicinity of the center, particles may remain outside the vicinity of the center of the substrate. Meanwhile, when the rinse liquid discharged from the single tube nozzle is landed on the middle of the radius of the substrate, although a relatively high washing degree can be obtained at the liquid-landing position, particles remain at locations other than that position. That is, when supplying the rinse liquid using the single tube nozzle, although the rinsing washing is preferably performed at the periphery of the liquid-landing position, the rinsing effect due to liquid spread to other locations on the substrate is small.
Also, when the rinse liquid discharged from the single tube nozzle lands on the substrate surface at a high angle, if the substrate surface is a fragile surface such as a copper wiring or a low-k film, it is damaged by landing of the rinse liquid discharged from the single tube nozzle, thereby causing defects at the liquid-landing position (for example, near the center).
Meanwhile, in the method of spraying the atomized washing liquid from a spray nozzle above the substrate outside to land on the substrate surface, and in the method of discharging the rinse liquid from the porous tube nozzle (bar nozzle) to land on the substrate surface, due to the discharge by the flat rotation mechanism, the removal particle or the residual chemical liquid is discharged toward the substrate outer circumference by the centrifugal force. However, since the liquid-landing area is wide toward the outer circumference from the center, the landed rinse liquid in the liquid-landing area interferes with the movement toward the outer circumference due to the centrifugal force of the removal particles or the residual chemical liquid, and pushes them back to the inside.
Also, in the central portion, since the washing liquid quickly moves toward the outer circumference by the centrifugal force, the rinsing efficiency is lower as compared to the area in which the washing liquid spreads by rotation other than the vicinity of the center. In addition, in the area liquid-landing by the spray nozzle or the porous tube nozzle, a quantity of air with which the rinse liquid comes into contact before landing increases, the oxygen concentration of the rinse liquid (for example, ultrapure water) originally supplied into the CMP device from the factory at the low oxygen concentration (for example, ≤10 ppb) increases (for example, 4.0 ppm=4000 ppb), thereby oxidizing the copper on the surface of the substrate.
The above-mentioned problems may similarly occur in the chemical liquid washing, without being limited to the rinsing washing as described in the above-described example.
It is desirable to improve a washing degree by causing a washing liquid to flow over the entire radius of the substrate in a washing device which washes a substrate, while supplying the washing liquid to the surface of the substrate such as a rotating semiconductor wafer.
A washing device of one embodiment includes: a substrate rotation mechanism which holds a substrate and rotates the substrate about a central axis of the substrate as a rotary axis; and a first single tube nozzle which discharges a first washing liquid toward an upper surface of the substrate held by the substrate rotation mechanism, wherein a first single tube nozzle discharges a first washing liquid so that the first washing liquid lands in front of the center of the substrate and the landed first washing liquid flows on the upper surface of the substrate toward the center of the substrate, and the device has a configuration in which a liquid flow on the upper surface of the substrate after landing of the first washing liquid discharged from the first single tube nozzle passes through the center of the substrate.
A washing device of another aspect includes a substrate rotation mechanism which holds a substrate and rotates the substrate about a central axis of the substrate as a rotary axis, and a spray nozzle which sprays a second washing liquid in a fan shape toward an upper surface of the substrate held by the substrate rotation mechanism, wherein the device has a configuration in which a maximum spraying quantity direction in which an spraying quantity is maximized in the spray nozzle is shifted close to the center of the substrate from the spray center.
A washing device of still another aspect includes a substrate rotation mechanism which holds a substrate and rotates the substrate about a central axis of the substrate as a rotary axis; a first single tube nozzle which discharges a first washing liquid toward an upper surface of the substrate held by the substrate rotation mechanism; and a spray nozzle which sprays a second washing liquid toward the upper surface of the substrate held by the substrate rotation mechanism, wherein the device has a configuration in which discharging of the first washing liquid by the first single tube nozzle and spraying of the second washing liquid by the spray nozzle are simultaneously performed.
A washing method of one embodiment is a washing method of rotating a substrate about a central axis of the substrate as a rotary axis and discharging a first washing liquid toward an upper surface of the substrate, wherein the method has a configuration in which the first washing liquid lands in front of the substrate, and the liquid flow on the upper surface of the substrate after landing passes through the center of the substrate.